Large triangular shaped object with 3 white lights and 1 blinking red light flew directly over us at very low speed and altitude.

We were walking to our house and looked up to see a very large triangular shaped object directly overhead. It had three white lights on it's underside and one blinking red light on the back. It was almost silent and was flying very low at a tremendously slow speed. It looked very flat and. I could not believe how slow it was moving. It took between 10 to 15 minutes to get out of sight. It was moving southeast.